Power hand tools having a tool unit, a tool body including a driving power source, and front and rear hand grips for holding the tool body are known. U.S. Pat. No. 5,065,476 (Patent Document 1) discloses a handheld portable tool including front and rear hand grips for both-hand operation, wherein the rear hand grip including a gas lever is rotatable about a horizontal axis of the tool unit and the tool body. In the power hand tool, the front hand grip is fixed to the tool body including the driving power source. The rear hand grip is rotatably supported by a supporting member provided at the tool body. A lock mechanism for automatically locking the rear hand grip at a predetermined operating position is provided at the supporting member and/or the rear hand grip.
The locking mechanism is unlocked only when the power hand tool is in a stop status or only when the tool unit is not driven, because a safety mechanism is provided for allowing the gas lever to be operated only when the lock mechanism is in a locked status.
Accordingly, the gas lever has an arc member at an end of its extended part. A moving locus of the arc member while the gas lever is rotated is overlapped with an upper limit surface of a detent pawl (a detent wedge). This prevents the gas lever and the lock lever from being operated at the same time.
The detent pawl (the detent wedge) is separately operated from the gas lever. Thus, there is a problem in that it is difficult to operate the detent pawl or the detent wedge and the gas lever by a single action. Further, the part of the detent pawl outside a frame may be actuated or damaged by a touched twig of a tree.
Accordingly, the present invention is developed to solve the problem by such operation that: actuating a control lever for controlling a drive power source in a tool body locks a rear hand grip to inhibit rotation of the rear hand grip; and releasing the control lever unlocks a rear hand grip to allow the rotation of the rear hand grip.